The sun causes all our weather because it heats the earth unevenly. The contrast between the hot parts and the cold parts of the earth turns our atmosphere into a powerful engine.  The engine keeps cold and warm air moving and makes changes in air pressure.  Those air pressure changes cause wind.  The heat of the sun also helps moisture to rise and form clouds, bringing rain, snow, or thunderstorms.  So all the changes in our weather come, at least indirectly from the sun.  For more on the summer sun, go here.

Blanket of Air

As the sun warms up the earth, the ground absorbs the heat, and reflects some of it back into the air.  That's one reason why it's usually warmer near the ground and cooler on the higher hills and mountains.  The atmosphere acts like a big blanket over the earth, holding in the warmth and reflecting it back to earth.


1. Let the Sun Shine

Take a wet cloth and wipe it across a blackboard.  Let the sun shine on part of the blackboard and watch the water evaporate.  Does the water evaporate faster in the sun or in the shade? Put some ice in the sun and some in the shade.  Does it melt faster in the sunlight or in the shade?

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